Drafting of locomotives



Dec. 26, 1939. N. F. LANE DRAFTING OF LOCOMOTIVES 2 Sheets-Sheet 1' Filed llay 19, 1937 A TTO INVENTOR.

Patented Dec. 26, 1939 v I UNITED STTES ATE T Price 6 Claims This invention relates to improvements in drafting of locomotives, and more particularly to improved means for effecting a balanced drafting of locomotive type boilers, together with automatic control facilities for the drafting means.

With the advent of high speed train operation, andconsequently greater requirements of steaming rate, it has become increasingly important to improve the efiiciency of draft-producing equipment, among other reasons, in order to enhence the steaming rate of existing types of 10- ccmotives and locomotive type boilers.

Numerous attempts have been made over a period of years, to the end of perfecting a mechanical system of drafting of boilers of, the

types mentioned; however, such attempts have met with only indifferent success, due in large part to the lack of provisions for effecting an automatic control of the draft-inducing and -producing agencies, these shortcomings being due at least in part to the lack of equipment for controlling the air displacement by such agency, as a function of or in response to variations in steaming requirements of the engine or boiler. So far as is known, no automatic control of mechanical drafting equipment has appeared in the art, but for the few devices which to date have been definitely proven unsatisfactory for their.

intended purpose. It is accordingly a major object of the present invention to provide a fully automatic control system, responsive to boiler steam pressure or boiler steaming requirements, to influence the mechanical drafting means utilized in connection with boilers of the types noted. A number of attempts have been made in the past, but with no degree of success, to draft locomotive type boilers mechanically through the use of an induced draft fan or blower, generally located in or adjacent to the smoke box. It has also been attempted to augment the volume .of air utilized for combustion, by the installation of forced draft fans or blowers of various types, serving to introduce the combustion air under ap-ositive pressure, through or beneath the grate bars. Neither of these devices or methods is, considered alone, fully satisfactory for the purpose of drafting locomotive type boilers, largely because of the widely varying pressure conditions existing between the zones in and adjacent to the fire box, and those zones in which the air, charged with solid particles resulting from combustion, exists at a high temperature, as in the smoke box. With the use of a forced draft system alne,,the zones of combustion are .,put under a substantial positive .pressurecreating a tendency at times for the gases and flames to be driven out through the fire door. On the other hand, utilizing only an induced draft blower, there results a partial vacuum in the zone of combustion. Thus at the numerous times of opening the fire door, there results a detrimental inrush of cold air which reduces the temperature of the gases of combustion and reduces the heat otherwise available to generate steam. It is accordingly an additional object of the present invention so to regulate the speeds, and hence the displacements of the fore and aft blowers, that there is maintained a pressure approximating atmospheric in the combustion chamber. This arrangement results in what may, for convenience, be termed a balanced draft system.

'It is a still further important object of the invention to provide, as a part of or adjunctively to abalanced draft system of the type described, a full automatic control arrangement therefor, whereby the speeds and displacements of the forced draft and induceddraft blowers may be not only proportioned correctly, but may bevaried directly and automatically in keeping with steaming requirements.

Still further objects of the invention may be noted as attained in an improved design and structure of blowers or fans for the purposes noted, including features of design which greatlyenhance the efiiciency of the blowers; the provision of expedients for ,materially prolonging the life of the blower parts subjected to the gases and particles resulting from combustion; improved cooling means for certain elements of theinduced draft blower, andnumerous other objects which will hereinafter appear from the following detailed description, considered in connection with the accompanying drawings of a presently preferred, exemplary embodiment of the invention, and in which:

Fig. 1 is a vertical longitudinal section of a locomotive boiler equipped in accordance withthe present invention, certain parts beingshown in elevation, and Fig. 2 is a schematic or diagrammatic representation of the control system, certain parts thereof being shown in forms approximating their preferred physical embodiments.

Referring now by characters of reference to the drawings,the,boiler shell is indicated at H], the fire box at H and the grate, which may be of any suitable or conventional construction, is characterized by the grate bars I2. Below the grate bars is a substantially air-tightashpan I3.,provided with a clean-out doorl l. Therear flue sheet is indicated at l and the flues at IS, the latter terminating in the usual manner, in a front flue sheet l1 forming the rear wall of the smoke box IS. The fire door, which mai be of usual type in case the boiler is hand-fired, is shown at 25, and to show the relation of parts in a locomotive of usual type, the cab structure is indicated in dotted lines and designated generally at 26. As thus far described, with the exception of the special air-tight ash pan IS, the parts are or may be of conventional construction.

In keeping with the present developments, air is supplied to the ash pan, beneath the grate bars, through a supply pipe 39. This may be made of any suitable or desired length and preferably extends over a substantial part of the total length of the grate. For better distribution of air, the pipe 30 may be provided With t-uyeres or the like 3|. Air is supplied under pressure to the pipe 30 as by a pressure-type fan or blower, Which is preferably of centrifugal type, and indicated at 35. This blower is conveniently powered by direct connection to a steam turbine 36, supplied from the boiler and controlled by means hereinafter described.

It is a preference to utilize, for better control and for better distribution of air of combustion, two of the units 36-3536, each'located somewhat laterally of the center line of the grate. Dependent however upon the arrangement of air distribution piping, a single, or any desired number of such units may be utilized, although only one is shown for convenience of illustration.

Proceeding now to a description of the parts internally of the smoke box, in the front end structure of the locomotive boiler, it is my preference to substitute for the usual front clean-out door, a mounting frame 40 which is conveniently secured in place of the clean-out door as by studs 4| The mounting frame 46 is of hollow construction and serves to carry, partially internally thereof, a turbine base 42 carrying a high speed fan-driving turbine 43. The enclosure of the turbine is completed by a hollow sheet metal cap or nose structure 45, provided with cooling louvres 46 which are so arranged and directioned as to induce a circulation of air within the frame 40 and cap 45, such circulation resulting in part from the motion of the locomotive.

The bearings of the turbine and fan assembly are indicated at 56 in the front, and at 5| in the rear of the turbine, the latter bearing serving also as a journal for the fan, hereinafter described, the turbine shaft 52 being extended rearwardly of the turbine and provided with a tapered portion 53 for receiving the hub portion 54 of the blower or fan. The latter is characterized by a plurality of curved centrifugal-type blades of reasonable number, preferably seven. It is a further important provision, greatly augmenting the life of the blades which are normally subjected to very high temperatures and the abrasive effects of cinders and the like, that the blades 56, each be completely coated to a depth of between A and inch with stellite, which retains its hardness almost indefinitely even under protracted periods of subjection to the high temperature gases and solids. It will appear that the hub portion of the fan, as well as the shafting and bearings therefore are more or less completely housed and isolated from the zones utilized for conducting the gases of combustion. This housing is completed through a structure 60, complemental to the framing or support structure 40, this support structure being provided with an apertured partition 6|, a central aperture of which is provided with packing elements 62 tending to prevent the travel of lubricant along the shaft and into the zone of the fan proper. For the purpose of promoting air circulation through the chamber about the turbine and shaft bearings, it is my preference to utilize a cooling fan 63, the blades of which are pitched in a manner to coact with the air currents normally created by the motion of the locomotive and to impart a definite direction to the cooling air entering and leaving through the louvres 46 of the nose portion 45.

The induced draft fan 56 preferably'operates at a substantial speed, in order to obtain the requisite displacement, and to realize this displacement through use of a fan which is not of excessive diameter and power requirements, and yet may be disposed within the space usually available therefor in the smoke box. This high speed of operation would ordinarily result in a substantial turbulence and eddy effects which, but for the provision of air-deflecting and -directing devices to be described, would materially impair the best efii'ciency of the induced draft fan, in its cooperation with the exhaust from the engine cylinders. To the end of assuring a definite direction of output of air from the fan, there are provided a plurality of vertical, parallel directing vanes, one of which is shown in elevation at 66. These have a definite function in damping turbulence, and in tending to reduce the discharge fiow from the induced draft fan, to a substantially rectilinear path.

The substantially elbow-shaped fitting 10 is employed to connect an annular structure H and a supporting ring 12 for the directing vanes. The member I0 is also provided with an upper outlet flange connection 75 providing a connection to the stack 16, and with a lower flange connection '11 assembled to the exhaust fitting 80, from which connection is made through a pair of conduits, one shown at 8|, to the engine cylinders. The latter elements are or may be of conventional construction.

From the foregoing it will appear that as the air discharged from the induced draft fan 56 is directed upwardly by the fitting 10, this discharge air stream will pick up and merge with the steam from the exhaust, and is so directed as to provide a definite ejector effect .in a manner tending to reduce exhaust back-pressure on the cylinders. Otherwise expressed, the design of the induced draft fan and associated parts is such that at no time will it oppose in any way the free egress of exhaust steam from the fitting 80, but on the contrary, is definitely designed to aid the evacuation of this and connected conduits, after the manner of an ejector. It will be noted as unnecessary to employ any of the usual types of exhaust nozzle in connection with the system proposed.

It is preferred, in order to avoid subjecting the fan blades and associated structure to needless abrasive effects, to provide a cinder screen through which the flue gases are caused to pass. A convenient location and structure of such an element is indicated at 85, showing a frusto-conical screen member of smaller diameter at its rear end and of larger diameter at its forward end. The slope and mounting of this screen 85 is such that, as it is subjected to the impact of cinders and solid particles in the flue gases, such particles will fall away from the screen by gravity, to a zone in the lower portion of the smoke box, whence they may be periodically reshown) draft introduced under the grates, while a tur-- bine-blower assembly of 100-105 H. P. bears about the correct proportion in the case of the front end assembly. K

To be sure, both sets of blower assemblies are required to handle all of .the air required for combustion of the fuel. However, it is noted that the volume of air to be displaced by the forced draft blower or blowers, is only about onehalf of the volume of the gases to be displaced by the induced draft blower assembly. This is due to the substantial difference in volume because of the increased temperature of the gases in the smoke box. The function of the forced draft blower is primarily to create a suiiicient initial pressure to impel the air through the bed of fuel and the grates; thus the induced draft blower is required only to draw the gases through the boiler tubes and smoke box. It is obvious from the foregoing that it is more efiicient to employ a balanced draft system than merely an induced draft system alone, or a pressure draft system, of itself.

Proceeding now to a description of the means .--by which is elfected an automatic control of the blowers in keeping with the steam pressure or steaming requirements of the boiler, there is seen (Fig. 2) that this type of control involves, at leastin part, an influence of the main steam supply, a conduit for this purpose being indicated at 90, which serves directly to affect a control unit designated generally as 9!. This unit is conveniently of a type involving a metal bellows indicated at 52. connected to the boiler as through the pipe 99, and through a lever connection 93,

serves to actuate a pendulum-type control lever 94, pivotally mounted on a control panel 95. The

lever Q4 includes a pair of horizontal arms proable types of switches now available being suitable for this purpose.

The electrical circuit may be considered as having its origin in either of a pair of supply leads Hi5 and I96 taken with a ground leg of the circuit. The leads are conveniently connected to the usual 32 volt supply system of the locomotive, and accordingly may be energized through the generator or storage batteries, or both.

The circuits originating in the control leads H35 and hit, are continued beyond the control panel designated generally at I !0, through a pair of conductors III and- I I2, a ground wire H3 being provided in the circuit relation indicated, and electrically connected to the lever 94 in the example disclosed. I i

.The leads III and H2. are continuedinto a control panel I I5, the latterbeing provided with a p-ivo-tally mounted, pendulum-type switch lever I I6, provided similarly to the lever 94, with horizontal arms, the extremities of which carry contacts II! and 4 I8, serving after the manner of the elements 98, 99 to control the circuits through a pair of switchcontacts indicated at H9 and I20, respectively arranged in the lines I12 and ill. be similar in design and capacity to the switches associated with the panel 95. Beyond the switches on the panel l I5, the circuits are continued through leads I22 and H3, a ground wire I2 3 being provided for return purposes, and a ground connection effected as at I25. It will have appeared that the control circuit is of the type known as a single wire system, in which one side of each circuit is completed througha grounded leg which may conveniently consist,'in part, of the metal portions of the locomotive Y structureand associated parts.

There is by preference mounted on the control panel I I5, and operatively connected to the pendulum lever E16, a variable volume control chamber'indicated at I30, and provided, for example, with a movable diaphragm I3 I, or in lieu thereof a piston (no-t shown), or some equivalent of the diaphragm or piston. To the diaphragm, for example,I is connected a control rod I32 pivotally co'nnectedto the lever I I5, the movement of this lever under the influence of the diaphragm, being opposed bya variably-loaded compression spring E35, the loading of whichis subject to adjustment as through threaded elements and lock nuts, the assembly of which is indicated at I36. The variable volume control'chamber I3!) is suppliedinternally with air under pressure through a conduit I 49, which has its origin or entrance end, in the boiler structure at such loca- The switches IlI-!I9. and II8!20 maytion as to maintain the conduit under a pressure The control circuits are each completed beyond the panel I I5, through the control wires I22 and I29, the former being connected to a pair of similarly disposed solenoid windings I45 and I46, for the energization thereof, the return circuit from each such winding being completed through the leads i l! and i 58 connected to the ground lead I24, grounded at I 25. In similar manner, the leads I23 are connected to a pair of similarly disposed electromagnets or solenoids I49 and I59, the return connections from which are completed through the conductors I41 and 148 to the ground at I25. It will have appeared that the solenoids or electromagnets are related in pairs, one pair comprising the magnets I45 and M9, and the other comprised of solenoids I46 and I50. Each of the pairs of magnets is provided with a common, double-end armature structure indicated generally at I5I and I52, and the armatures of each such structure connected through plungers I53 and l54 to an adjacent air control valve of piston and cylinder type. These air control valves include a piston 955 operating in a cylinder I56 on the one side, and'a piston I51 operating in acylinder Hilton the other side. The cylinders I56 and I53 areof double-end type,

(iii

the cylinders being provided with air under pressure, as from the brake system of the locomotive, through air inlet pipes I50 supplying the cylinder I56, and I5I supplying cylinder I58. Each cylinder is provided with a pair of outlets respectively near the upper and lower ends of the valve, these outlets being indicated in the control for the forced draft turbines, at I19 and HI, and in connection with the cylinder I58 serving to control the induced draft blower turbine, at I12 and I13.

The paired air discharge tubes or conduits from each valve cylinder, are connected respectively to the upper and lower ends of a double-ended cylinder-and-pistcn control unit, or air servomotor, the motor cylinders being indicated. at I16, for the forced draft turbine control, and I11 for the induced draft turbine control. These cylinders are each provided with a power piston, the pistons being designated respectively at I18 and I19.

Each power piston is connected through a rod, such as I85 or I86, through a pivotal connection I 91, and I88, to a steam valve. The two steam valves illustrated are preferably of so-called chronometer type, providing a plurality of steamadmission passages through the body of the valve, which are graduated and so arranged that the first position of each valve provides an idling regulation of the associated turbine or turbines, while the remainder of the positions provide, in sequence, for augmenting the steam supply to, and hence serve to enhance the air displacement by the turbines controlled therethrough. Through the provision of links such as I99 and I9I, the movements of the servo-motor pistons are translated to the valve actuating arms I95 and I99, operatively associated, respectively, with the valve bodies I91 and I98. The former of these serves to control the flow of steam through a boiler-connected steam supply pipe I99 and a forced-draft turbine supply pipe 298, and the latter valve controls the flow of steam through a boiler-connected steam supply pipe 2IlI, thence to the supply line to the induced draft turbines, indicated at 202.

In the case of Stoker-fired boilers, assuming according to usual practice that the stoker is steam-powered, either through a reciprocating unit or a turbine and reduction gear assembly, it is preferred that the steam supply for the stoker drive be derived from the supply pipe such as I99. This arrangement is utilized so that the valve I91, in augmenting or decreasing the steam supply to the forced-draft fan turbine, will proportionately augment or decrease the steam supply to the stoker drive. But for this expedient, the decrease in air supplied to the grates would not necessarily result in a corresponding reduction in rate of fuel supply to the grates. It will be seen, however, that by controlling both the forced-draft turbine steam supply and the steam supply for the stoker drive through the same, or through separate correspondingly operated valves, the rates of air feed and fuel feed are automatically coordinated through the control system described. It has been found convenient in practice to provide the steam supply pipe 200 under the control of the valve I91, with at least a pair of branches, one thereof. such as 295 leading to the steam supply for the stoker drive, and another shown at 296 being directed to the forced-draft turbines. If desired, hand valves 291 and 208 may be utilized for manual regulation or proportioning of the flow of steam through the respective branches 205 and 206.

The operation of the control system may be briefly reviewed by noting that, as the steam pressure increases in the boiler and hence in the conduit 90, and hence that, as the steaming requirements of the boiler decrease, the increased pressure will influence the unit 9| in a manner to swing the lever 94 to the left, thus serving to bring the contact 98 into engagement with the stationary contact I00, thus completing the circuit through the ground and through the control legs I06 and H2, thence, assuming the switch II1-I I9 to be closed, through the lead I22 so as to energize the upper coils I45 and MB of the solenoid valve-operating assembly. This will cause the armature assemblies I5I and I52 to be actuated upwardly, into the positions shown by the drawing, raising the pistons I55 and I51, closing the inlets I19 and I12 to the servo-motors, but opening the inlets HI and I13. This actuation will have the effect of putting the air pres sure from the air supply system against the lower faces of pistons I18 and I19 of the servo-motors, with the effect of raising, in the positions shown, the valve-actuating levers I95 and I95. If the circuit remains closed as indicated, for an appreciable time, the valves will thus be actuated toward steam-restricting positions, and will be brought to positions in which the steam supply is only sufiicient to cause the turbines and blowers to operate at idling speed.

It will have been noted that this actuation is dependent upon the closed position of switch I I6-I I1, this switch being closed only in response to a predetermined but substantial air pressure in the overfire zone. It is accordingly seen that the controls are responsive primarily to the steam supply and boiler steaming requirements, and also secondarily subjected to the influence of the overfire draft pressure. This is true since the one of the switches carried by panel H5, which is closed, the switches being operable only one at a time or selectively, is determined by draft conditions.

Assuming now an opposite set of conditions to prevail, namely a relatively reduced steam pressure and a relatively reduced draft pressure, the influence of the bellows unit 9I will operate to close the switch 99IUI and permit the switch 98I00 to open. Assuming the switch 99-IDI to be closed, and assuming a low draft condition to prevail in the overfire zone, so that switch I!8-I2I] is closed, a different control circuit will now be completed, one side through the ground, and the other side through the leads I 05, III

and I23, so that the coils I49 and I5!) become energized, at the same time coils I45 and I46 being deenergized. This will result in a movement of the armatures I5I and I52 to their lowermost positions in the figure, in a manner to move the valve pistons I55 and I51 to the opposite ends of the valve cylinders. Under this condition, air is excluded from the lower end of the motor cylinders and admitted to the upper ends thereof, assuming them to be mounted in the positions shown. Thus the valve levers I95 and I96 will be actuated to a steam-admitting position, the extent of their opening depending upon the amount and duration of air admission to the servo-motor, as influenced by the controls described. This set of conditions serves to increase the speed of the forced draft turbines as well as the speed of the induced draft turbine in a manner to increase the draft supply, and similarly the steaming rate. It is to be observed that the increase or decrease of turbine and blower speeds, is always such as to keep the induceddraft and forced-draft units correctly proportioned in output.

It is preferred to provide for an adjustment of the extent of actuation of the valve-operating levers, as through the provision of a number of openings selectively utilized for the connection of a pivot pin on each of the links 190 or I!!! to the associated valve lever. It is also preferred so to set the control instrument such as the steam-pr ssure responsive unit SI, and the draftresponsive unit carried by panel I I5, so that an appreciable range of pressure occurs between opening and-closing valve movements. This is preferably at least a five pound pressure differential and in many cases it is advisable to provide for a ten pound difference in setting, 50% to prevent unnecessary hunting of the controls in response to minor variations in steam pressure. Similarly, the setting of the draft responsive control avoids excessive changes in the control circuits and avoids needless control actuation in response to minor variations in draft pressures.

It is desirable in most installations, to provide for a manual control of the steam supply through the turbines, in case of failure of any part of the control system, or so as to enable the operator, as in an emergency, tomeet extreme conditions by manually controlling the amount of draft. Among the instruments preferably so provided, is a master steam pressure control indicated at 209, a draft control for the forced draft fans shown at 2N3, and a chronometer type throttle valve designated as 2H. posed at a convenient point of access to th engineer, as in the cab 26.

It will have appeared that the system described serves to compensate for differences in fuel bed according to type of fuel being burned, and to compensate for other variations in specific operating conditions, so that the speeds of the fans are correctly proportioned, through an automatic control, at all times. well as the stoker operation, and hence the rate of fuel feed, are subject to control under the, influence of steam pressure, and hence of steaming rate. The ideal operating condition is, of course, to maintain the optimum steam pressure to meet a given set of working conditions of the locomotive, and when desired, to maintain as high a pressure as possible without loss of steam through popping of the safety valve, which obviously resultsin inefficiency and loss of thermal values.

From the foregoing it will have appeared that the system described fully attains each of the several objects above specifically enumerated, as well as those implied from the description.

While the invention has been described by making specific reference to a presently preferred embodiment of the invention, the description is not to be understood in a limiting sense, since obviously many changes may be made both in the draft-producing agencies as well as in the control apparatus, without departing from the spirit and full intended scope of the invention as defined by the claims hereunto appended.

I claim as my invention:

1. In combination in a steam locomotive, a balanced draft producing and control system including a turbine-driven blower of forced-draft type, having its outlet ahead of the grates and adapted to force a supply of combustion air therethrough, a turbine-driven induced-draft blower located in the smoke box of the locomotive boiler, a fitting forming a discharge passage These are preferably dis- Concurrently both fans as directed from the induced draft blower and so directioned as to impart a steam eductive effect to the engine exhaust passages into the stack, and such that exhaust impulses coact in the draft-inducing action of the last said blower, the 5 twoblowers being so proportioned with respect to eachother as to maintain in the drafting system between the blowers, a pressure substantially of the orderof atmospheric; a control system for the blowers including a pressure-responsive ap- 1, 10

paratus having a loaded pressure-movable element subjected to draft pressure in an overfire zone, electromagnetic means in throttling relation to the steam supply of the turbines associated with the blowers, means for varying the proportionate throttling effect of said electromagnetic means, and means for varying the loading and response of said pressure movable element.

2. In combination in a steam locomotive, ango balanced draft producing and control system including a turbine-driven blower of forced-draft type, having its outlet ahead of the grates and from the induced draft blower and so directioned 30 as to impart a steam eductive effect to the engine exhaust passages into the stack, and so connected to the exhaust passages that the exhaust impulses coact with the blower in its draft inducing effect, the two blowers being so propor- 5 tioned with respect to each other as to displacement capacity, as to maintain at all times during blower operation, a substantially balance draft pressure condition between the grates and the induced-draft induced-draft blower, and to maintain in the drafting system between the blowers, a pressure substantially of the order of atmospheric; a control system for the blowers including a pressureresponsive apparatus having a loaded pressuremovable element subjected to draft pressure in an overfire zone and above the fire arch, electromagnetic means influenced by said pressure-responsive apparatus, separate fluidpressure control devices, each in individual throttling relation to the steam supply to one of the blowers, both said devices being subject to control of said electromagnetic means, and arranged to effect concurrent throttling actuation in the same direction, means for varying the proportionate throttling effect of said devices on the two blowers,

as influenced by said electromagnetic means, and means for varying the loading and'response of said pressure movable element, whereby to provide for variation in range of pressure influence on the blower turbines.

3. In a draft-producing and controlling system forlocomotive boilers, an air displacement device or blower of forced-draft type, arranged to anced-draft type for locomotive boilers, a forced:

draft blower arranged to supply air under pressure to the grates, an induced draft blower located substantially beyond the zone of primary combustion, a steam prime mover for each of said blowers, separate throttle means for each of the prime movers, and combined air pressure and electromagnetic means for effecting corresponding throttling effects of the prime movers, the last said means being responsive to variations in draft pressure in an overfire zone between the blowers, and an exhaust ejector fitting adjacent the discharge side of the induced draft blower whereby the exhaust impulses coact with the induced draft blower in maintaining desired draft pressures in the zones between the blowers.

5. In combination in a steam locomotive, a mechanical drafting system of balanced-draft type including a steam turbine, a forced draft blower driven thereby and arranged to supply air under pressure to the grates, an induced draft blower located in the smoke box of the boiler, a drive turbine therefor, means for controlling the admission of steam to the blower turbines, and hence controlling blower speeds, in response to variation in draft pressure in an overfire zone, a discharge fitting connected to the outlet side of the induced draft blower and directly connected to the blower stack, a locomotive exhaust connection opening into said fitting adjacent the discharge of the induced draft blower, and a plujacent and beneath the grates, a turbine driven induced draft blower in the locomotive smoke box, a discharge fitting for said blower extending from the outlet side thereof to the locomotive stack, an exhaust connection from the locomotive cylinders into said fitting, so arranged that the exhaust impulses augment the drafting efiect of the induced draft blower, and means for throttling the supply of steam to the blower turbines in response to variation in draft pressure in a zone adjacent the fire arch of the boiler.

NEWTON FRANK LANE. 

